Epilepsy Surgery: Vagus Nerve Stimulation
The vagus nerve is one of the cranial nerves that originates in the brain and is part of the autonomic nervous system, which controls involuntary body functions. The nerve begins at the brainstem and passes through the neck, traveling to the chest and abdomen. It is responsible for regulating the functions of internal organs. Specifically, it is involved in motor functions in the voice box, diaphragm, stomach, heart and sensory functions in the ears and tongue. It is also associated with both motor and sensory functions of the sinuses and esophagus.
Vagus nerve stimulation (VNS) is a device, similar to a pacemaker, which sends regular, mild pulses of electrical energy to the brain via the vagus nerve to alleviate seizures. The device is surgically implanted under the patient’s skin. There is no physical involvement of the brain in this surgery, instead the device battery (pulse generator) is implanted in the chest and wires are placed in the neck and positioned around the left vagus nerve. When the device is on, electrical pulses are sent through the vagus nerve to the brain. Patients cannot generally feel these pulses. VNS decreases seizure frequency by at least half in 40-50% of patients, but rarely eliminates all seizures.
VNS is a surgical intervention used to treat patients with drug-resistant epilepsy.
Individuals with any of the following criteria may be unsuitable candidates for VNS:
- A single working vagus nerve
- Diagnosis of refractory epilepsy for less than 2 years
- Heart arrhythmias or other heart abnormalities
- Dysautonomias (abnormal functioning of the autonomic nervous system)
- Lung diseases or disorders (shortness of breath, asthma, chronic pulmonary disease, etc.)
- Ulcers (gastric, duodenal, etc.)
- Vasovagal syncope (fainting)
- Pre-existing hoarseness
- Other relative contraindications for surgery
Patients with epilepsy commonly experience the following symptoms:
- Temporary confusion
- A staring spell
- Loss of consciousness
- Uncontrollable jerking movements of arms or legs
- Emotional responses such as fear, anxiety or déjà vu
Vagus Nerve Stimulation is used when a patient’s epilepsy does not respond to anti-seizure medications. See a doctor if any of the above symptoms are persistent for an extended period and are unresponsive to medications.
Before surgery, the patient is evaluated by a neurologist to determine if the type of epilepsy is best treated by VNS. The implanting neurosurgeon will take a full history and physical examination to ensure that the patient is a good surgical candidate.
This procedure, performed by a neurosurgeon, usually takes about 1-1.5 hours, most commonly under general anesthesia. It is usually performed on an outpatient basis. As with all surgeries, there is a small risk of infection. Other surgical risks of VNS include inflammation or pain at the incision site and damage to nearby nerves. The device may malfunction, similar to any other electrical device.
The procedure requires two small incisions. The first one is most commonly made on the upper left side of the chest where the battery is implanted (pulse generator). A second incision is made horizontally on the left side of the lower neck, along a crease of skin. This is where the thin, flexible wires that connect the pulse generator to the vagus nerve are inserted (lead). While this device is meant to be permanent, it can be removed if needed.
The device in the chest looks like a heart pacemaker. Newer devices may be smaller. When the battery is low, the chest device is replaced with a less invasive procedure which requires only opening the chest wall incision.
The stimulator is most commonly activated two to four weeks after implantation, although in some cases it may be activated in the operating room. The treating neurologist programs the stimulator in his or her office with a small hand-held computer, programming software and a programming wand. The strength and duration of the electrical impulses are programmed. The amount of stimulation varies by case, but is usually initiated at a low level and slowly increased to a suitable level for the individual. The device runs continuously and is programmed to turn on and shut off for specific periods of time — for example, 30 seconds on and five minutes off.
The settings will be primarily set by neurologists, but the will also be provided a handheld magnet to control the stimulator at home. For example, if the patient feels a seizure is about to occur, they can turn stimulation on or a loved can assist. The patient does this by swiping over the pulse generator site to deliver extra stimulation regardless of the treatment schedule. All maneuvers performed with the magnet can be done by the patient, family members, friends or caregivers.
Side effects are most commonly related to stimulation and usually improve over time. These may include any of the following:
- Increased coughing
- Changes in voice/speech
- General pain
- Throat or neck pain
- Throat or larynx spasms
- Muscle movements or twitching related to the stimulation
- Nausea or vomiting
- Impaired sense of touch
- Prickling or tingling of the skin
Of these, hoarseness, coughing, throat tickling and shortness of breath are the most common and are usually temporary. Altering the stimulation may relieve symptoms. Call a doctor with concerns.
- Laryngeal Motor Evoked-potentials as a Biomarker of Vagus Nerve Stimulation in Epileptic Patients (NEURO-LARYNX)
- Registry of Subjects With Drug Resistant Epilepsy and Treated With the VNS Therapy System. (CORE-VNS)
- Brodtkorb E, Samsonsen C, Jørgensen JV, Helde G. Epilepsy patients with and without perceived benefit from vagus nerve stimulation: A long-term observational single center study. Seizure. 2019 Nov;72:28-32: This study investigated the benefit of VNS in patients with drug-resistant epilepsy. The study concluded that benefit of VNS may be compounded by continuation of anti-epileptic drugs. Patients who are not receiving benefit from VNS should not continue the treatment and their systems should be revised.
- Ryvlin P, So EL, Gordon CM, Hesdorffer DC, Sperling MR, Devinsky O, Bunker MT, Olin B, Friedman D. Long-term surveillance of SUDEP in drug-resistant epilepsy patients treated with VNS therapy. Epilepsia. 2018 Mar;59(3):562-572: This is a long-term observational study which looked at the rate of unexpected death in epilepsy patients with VNS. The study found that the risk of unexpected death significnaly decreases in patients undergoing VNS therapy.
AANS Patient Pages are authored by neurosurgical professionals, with the goal of providing useful information to the public.
Julie G. Pilitsis, MD, PhD
Chair, Neuroscience & Experimental Therapeutics
Professor, Neurosurgery and Neuroscience & Experimental Therapeutics
Albany Medical College
Specialty in neuromodulation with research interests in treatments for movement disorders and chronic pain.
Research Coordinator, Neuroscience & Experimental Therapeutics
Albany Medical College
The AANS does not endorse any treatments, procedures, products or physicians referenced in these patient fact sheets. This information provided is an educational service and is not intended to serve as medical advice. Anyone seeking specific neurosurgical advice or assistance should consult his or her neurosurgeon, or locate one in your area through the AANS’ Find a Board-certified Neurosurgeon online tool.